Photographic vesicular materials and imaging process therefor

ABSTRACT

VISICULAR PHOTOGRAPHIC MATERIALS COMPRISING A POLYMERIC VEHICLE AND A LIGHT DECOMPOSABLE AGENT. THE POLYMERIC MATERIAL IS A MIXTURE OF A RESIN A AND A RESIN B. BY ADJUSTING THE RELATIVE PROPORTIONS OF THESE RESINS, THE PHOTOGRAPHIC GAMMA OF THE FILM CAN BE ALTERED. THE RESIN A IS AN ESTER OR ACETAL OF POLYVINYL ALCOHOL. THE RESIN B IS AN EPOXY RESIN, A PHENOL FORMALDEHYDE RESIN, A UREA-FORMALDEHYDE RESIN, A MALEMINE-FORMALDEHYDE RESIN, A CELLULOSE ESTER, A SILICONE RESIN, AN ISOCYANATE RESIN OR A COPOLYMER OF MALEIC ANHYDRIDE WITH STYRENE. PREFERABLY, THE AMOUNT OF RESIN A IS AT LEAST 50% AND THE AMOUNT OF RESIN B IS UP TO 50%.

United States Patent US. Cl. 96-48 11 Claims ABSTRACT OF THE DISCLOSUREVesicular photographic materials comprising a polymeric vehicle and alight decomposable agent. The polymeric material is a mixture of a resinA and a resin B. By adjusting the relative proportions of these resins,the photographic gamma of the film can be altered. The resin A is anester or acetal of polyvinyl alcohol. The resin B is an epoxy resin, aphenol formaldehyde resin, a urea-formaldehyde resin, amelamine-formaldehyde resin, a cellulose ester, a silicone resin, anisocyanate resin or a copolymer of maleic anhydride with styrene.Preferably, the amount of resin A is at least 50% and the amount ofresin B is up to 50%.

This is a division of prior US. application Ser. No. 768,943, filed Aug.12, 1968, now US. Pat. No. 3,498,786 which in turn is a continuation ofapplication Ser. No 403,663, filed Oct. 13, 1964, now abandoned.

The present invention relates to photography and, more particularly, tothe production of vesicular images.

Vesicular images are formed in a photographic film by small bubbles orvesicles of gas which are formed and trapped in the areas of the filmexposed to light and which refract light. Generally speaking, the filmhas a colloid or a resin coating or vehicle on a backing material and alight-sensitive agent or sensitizer, most commonly a diazo compound,dispersed throughout the coating. When the film is exposed to light, thesensitizer releases molecules of a gas-nitrogen in the case of diazocompounds. These ordinarily do not form vesicles immediately, but theydo so when the film is heated, presumably because the vehicle is relaxedsufiiciently on heating for the gas molecules to diffuse together intobubbles and for the bubbles to expand. The resulting vesicles make thevehicle opaque to transmission of light in the exposed areas and alsoreflect and scatter light so that they appear white.

Vesicular photographic materials have been of only limited use incertain applications because of lack of flexibility in the gray scale,or photographic gamma, they possessed. That is, in general it isdesirable to reduce the contrast or gamma of light-scatteringphotographic materials, while in other cases it may be desirable toincrease the gamma. It has been known to reduce the photographic gammawhile reducing the maximum obtainable density. However, the resultantloss of density range limits the usefulness of this technique.

It also is known to reduce the photographic gamma by treating avesicular photographic material in a heated aqueous fluid, as is morefully described in US. Pat. 3,149,971. This procedure gives goodresults. However, there is a need for other techniques which avoid theadditional process step required.

It is an object of the present invention to provide, in an improvedvesicular photographic film, means for adice justing the photographicgamma of the film in which the vehicle is comprised of a blend of tworesins to be designated further herein as resin A and resin B. lResin Ais a polymer containing an ester or acetal derivative of polyvinylalcohol; resin B is taken from the group consisting of epoxy resins,phenol formaldehyde resins, urea formaldehyde resins,melamine-formaldehyde resins, cellulose esters, such as celluloseacetate butyrate and cellulose nitrate, silicone resins, isocyanateresins, and copolymers of styrene and maleic anhydride.

The ester derivatives are generally obtained by polymerization of estersof vinyl alcohol with aliphatic or aromatic carboxylic acids. Thealiphatic acids are preferred, the most suitable being lower fatty andunsaturated acids containing up to about six carbon atoms, such asacetic acid, propionic acid, valeric acid, vinyl acetic acid or crotonicacid. However, higher fatty acids such as octanoic may be used,particularly in combination with lower fatty acids. Suitable aromaticacids include benzoic acid, naph thoic acids and phenyl acetic acid. Theester polymers may be obtained from the monomer by any conventionalpolymerization method, i.e., bulk, solution or aqueous emulsion ordispersion, in the presence of, e.g., a free radical or ionic catalyst,the details of which form no part of the present invention.

Polyvinyl acetals are generally made by reaction between aldehydes andpolyvinyl alcohol or polyvinyl esters such as polyvinyl acetate. It ispreferred that saturated lower aliphatic aldehydes be employedcontaining up to six carbon atoms, particularly butyraldehyde andformaldehyde, However, small amounts of higher aliphatic aldehydes oraromatic aldehydes such as benzaldehyde may be included. The polyvinylacetal polymers may contain small amounts of residual hydroxyl groupswhich have not been converted to the acetal derivative, or of acetategroups which have not been converted to hydroxyl. However, no more thanabout 60% of the hydroxyl groups, and preferably no more than 25% shouldremain as free hydroxyl groups, i.e., not converted to a derivativethereof.

It will be appreciated that while the above description of preferredpolymers has been directed to homopolymers, copolymers containing morethan one acetal, or ester group may be used. Thus polyvinyl acetals maycontain two or more types of acetal groups or, e.g., acetate units aswell as acetal. In addition, relatively minor amounts of otherethylenically unsaturated monomers containing one or more C=C groupsmaybe copolymerized, e.g., up to about 5%, as long as thecharacteristics of the polymer are essentially not altered so as torender it unsuitable.

Epoxy resins which may be used preferably are glycidyl ethers ofpolyhydric phenols derived by reaction of a polyhydric phenol withepichlorohydrin. For example, one

may use the glycidyl ethers of his phenol A having the formula CH3 nwhere n is a number up to about 10-15. In place of bis phenol A, othersuitable epoxy resins may be based upon mononuclear diand trihydroxyphenols and other polynuclear polyhydroxy phenols, such as resorcinol,hydroquinone, pyrocatechol, phloroglucinol, bis phenol F, 2,4-4'-trihydroxydiphenyl dimethyl methane, 4,4-dihydroxy biphenyl, and thelike. In addition, one may use expoxidized unsaturated oils, asdescribed more fully in the Encyclopedia of Chemical Technology, SecondSupplement Volume (1960) and other epoxide group-containing materials.However, the glycidyl ethers of bis phenol A are preferred and arereadily available commercially.

Phenolic, urea or melamine resins which are used are condensates of aphenol, e.g., phenol and p-alkyl phenols, melamine or urea withformaldehyde. A wide variety of these materials are known andcommercially available. For example, detailed descriptions may be foundin the Encyclopedia of Chemical Technology, volume 1 (1947) pages741-769, and volume (1953) pages 335-368.

The styrene maleic anhydride copolymer may be prepared by anycopolymerization system known for these monomers, e.g., bulk, solutionor emulsion polymerization in the presence of a catalyst. Lowermolecular weight materials are desirable from the standpoint ofcompatibility and solubility, but higher molecular weight resins alsomay be used.

The isocyanate resins are isocyanate-ended prepolymers derived byreaction of an excess of polyisocyanate such as tolylene diisocyanate orp,p'-diisocyanatodiphenylmethane with a polyester, polyether or apolyesteramide. Such materials normally are used with additional amountsof polyester, polyether or polyesteramide, and with or without Water, inthe making of polyurethanes. They are described in prior US. patents andin Polyurethanes, Chemistry and Technology by Saunders and Frisch andPolyurethanes by Bernard A. Dombrow.

The silicone resins, as are known, are polymers in which the repeatingunits have the formula In which R may be alkyl, preferably lower alkyl,e.g., methyl or ethyl, aryl, e.g., phenyl, tolyl, xylyl or naphthyl,aralkyl, e.g., benzyl, alkenyl, e.g., vinyl or allyl, or cycloalkyl,e.g., cyclohexyl. Other groups which may be attached to the silicon atomare hydrogen, -ONa, -OK, or --OR where R has the same meaning as above.As will be appreciated, depending on the value of n in the aboveformula, the silicone may be linear, branched or crosslinked. For themost part, silicones which are linear or slightly branched but notextensively cross-linked are preferred because these tend to be moresoluble in the organic solvents used in making films. Suitable examplesare polysiloxanes, having repeating units of the general formula R s'i-Oit 2 with end groups such as R R R-Sior I-IOS i-- where R is methyl,ethyl, propyl or vinyl. Detailed descriptions of such polymers may befound, for example, in The Encyclopedia of Chemical Technology, vol. 12,page 393 and An Introduction to the Chemistry of the Silicones by E. G.Rochow, 2d. ed., 1951.

The resins A and B are suitably blended by dissolving in a mutualsolvent or by dissolving them in separate solvents and mixing thesolution together. The resulting resin solution is mixed with thesensitizer, preferably first dissolved in a separate solution, and theresulting mixed solution is coated on a substrate and dried, forexample, by heating in an oven at 240 F It will be observed that some ofthe resins B may be capable of reacting with acetate,

hydroxy or acetal groups of resin A. Consequently, a certain amount ofcross-linking may take place, e.g., during this drying step.

After the film is thus prepared, there are at least three differentmethods of processing it. In one form, the film is exposed toimage-forming light, e.g., by being placed in contact with atransparency and exposed to light passing through the transparency.Then, the film is heated to 160-300 F. for to 3 seconds. This willproduce an image of the opposite photographic sign from thetransparency. Thus if the transparency is a negative, a positivevesicular photograph will result.

A second processing system which can be used is first described in US.Pat. No. 2,911,299. In it, the film is exposed to image-forming lightand gas released by the sensitizer is allowed to diffuse from thevehicle at a temperature too low for development to take place. Then thefilm is exposed overall to uniform light, which activates undecomposedsensitizer, and is heated to cause development at 160300 F. for to 3seconds, either during or shortly after the second exposure, but beforethe gas has substantially diffused from the film. This results in imageformation in areas not originally struck by light and an image of thesame photographic sign as the transparency. Thus a negative transparencyresults in formation of a negative vesicular photograph which might becalled a reversal image or direct image.

The third processing system is that described in US. Pat. No. 3,457,071.In that system, the film is exposed to image forming light of relativelylow intensity for at least about 0.5 second and preferably for at leastabout 2.0 seconds. That is, the light is of low enough intensity thatthe film does not receive a normal exposure in less than 0.5 second andpreferably 2.0 seconds. Then the film receives an overall exposure oflight intensity which is sufficient to expose the film in less than 0.2second and preferably less than 0.01 second. Overexposure or longerexposure can be tolerated, but there must be sufficient light toproperly expose the film during the indicated time. This procedureavoids a separate diffusion step as used in the method of US. Pat. No.2,911,299. In some cases, no heating is required to cause development,and the image appears spontaneously. However, in other cases, someheating may be used to advantage, as more fully described in US. Pat.No. 3,457,071.

Any suitable substrate may be employed for the photographic materials.For films, the preferred materials are films of Mylar (polyethyleneterephthalate), polyethylene and polypropylene. Paper backings, metalplates and glass slides also are useful for certain applications. Thus,while films are referred to herein, it will be understood that theinvention embraces any backing layer.

It has been found that by mixing resins A and B in different proportionsit is possible to adjust the photographic gamma of the films andfrequently to increase the photographic density. As the amount of theresin B is increased, the degree of change of photographic gamma willgenerally increase accordingly. The exact proportions used will, ofcourse, vary according to the desired result. For any given pair ofresins, it is possible to determine the effect of changes in proportionsby making films from them and determining the value of gamma byconventional sensitometry. A graph is then made in which gamma isplotted as a function of composition, which permits selecting the exactcomposition for any desired 'value of gamma. However, in general, theamounts of the resins will fall within the ranges to 50% resin A and 0to 50% resin B. It also has been found that alterations in the relativeamounts of resins A and B change the photographic speed and projectiondensity of the film. In general film speed increases when the contrastis reduced, in a manner somewhat analogous to commercially availablesilver halide films.

The following examples illustrate the practice of the invention, allparts being by weight.

5 EXAMPLE 1 The following constituents were combined with stirring toform a solution:

Parts Butyraldehyde polyvinyl acetal (80% acetal, -2.5

acetate, l7.52l.0% hydroxyl) 25 General Electric methylon 75-108 1,4dioxane 200 p-Diazo N,N-dimethyl aniline zinc chloride salt 4Acetonitrile 80 Methylon 75-108 has the formula ?CHZCH=CH2 Hat-n)(0112011).

Where n: l-3.

The solution was applied to a backing layer of Mylar film and dried.Then the film was exposed to light from a 500 watt tungsten filamentincandescent lamp spaced about 3 inches from the film through an imagebearing transparency for twenty seconds and developed by heating for twoseconds at 240 F.

An image was obtained which showed a maximum projection density of 2.74.

EXAMPLE II The following constituents were carefully mixed in an openvessel with stirring continued until a uniform solution was obtained.

Parts Formaldehyde polyvinyl acetal (50% acetal, 40

50% acetate, 5.06.5% hydroxyl) 25 SMA 400A 1 5 1,4-dioxane 100 p-DiazoN,N-dimethylaniline zinc chloride salt 4 Acetonitrile 80 1A copolymer ofstyrene and maleic anhydride which is a dry powder, has a molecularweight of 700, a melting range of 50-70 C., an acid number of 415, aspecific gravity at 30 C. gms., 100 ml. acetone) of 0.53, a bulk densityof 37.9 lbs/fit. and a true density of 76.4 lbs./ft.

The resultant solution was coated on a glass plate which was dried,exposed to light through an image bearing transparency and developed asin Example I. The image showed a maximum projection density of 2.68.

EXAMPLE III Example II was repeated using as the constituents of thesolution:

Parts Butyraldehyde polyvinyl acetal (88 acetal, 0-2.5

acetate, 9-13.0% hydroxy) 25 Resimene 881 1 5 1,4-dioxane 100 p-DiazoN,N-dimethyl aniline zinc chloride salt 4 Acetonitrile 80 A melamineformaldehyde resin composition Type III, 60i2% solids with 20% butanoland 20% xylol having an acid number less than 1 (mg. KOH to neutralize 1g. resin solids) and a viscosity L-P (Gardner-Holt bubble tube standardat 25 (3.).

The image showed a maximum projection density of 2.76.

EXAMPLE IV Example H was repeated, using as the constituents of thesolution:

Parts Formaldehyde polyvinyl acetal (82% acetal, 9.5-

13.0% acetate, 5.0-6.5 hydroxyl) 25 SR-82 1 5 1,4-dioxan 100 p-DiazoN,N-dimethyl aniline zinc chloride salt 4- Acetonitrile A silicone resinavailable as an uncatalyzed, light strawcolored solution in xylolcontaining 60i1% solids, having a irtiglctlfic gravity of 1.06 and aviscosity of 5-30 cps. (Gardner- The image obtained showed a maximumprojection density of 2.58.

EXAMPLE V The following materials were combined in 80 parts ofacetonitrile to form a solution:

Parts Butyraldehyde polyvinyl acetal (80% acetal, 02.5%

acetate, 180-20% hydroxyl) 25 Mondur S 5 1,4-dioxane 180 p-DiazoN,N-dimethyl aniline zinc chloride salt 4 Mondur S is a light-colored,stabilized polyisocyanate adduct known for use with polyester resins inthe formulation of bake-type one-component room temperaturestableurethane coatings. It has a specific gravity of 1.26- 1.28, a totalsolids content of about available NCO, 11.5l3.5% and a softening pointof 80l20 C. i

The resultant solution was coated on a thin film of Mylar and dried inan oven at 240 F. for 5 minutes. The dried film was placed in contactwith a microfilm transparency and exposed to light through thetransparency from a mercury arc lamp (General Electric H-A4 IT) spaced 2inches away for 20 seconds. The film was then developed by heating to240 F. for two seconds.

An image was obtained which showed a maximum pro jection density of2.47.

In the following examples, solutions were prepared from the constituentsindicated and films were made as described in Example I. Then the filmswere exposed and developed as also described in Example I.

EXAMPLE VI Parts Butyraldehyde polyvinyl acetal (80% acetal, 0-l.0%

acetate, 180-20.0% hydroxyl) 25 Araldite 6097 1 5 1,4-dioxane 250p-Diazo N,N-dimethyl aniline zinc chloride salt 4 Acetonitrile 80 A bisphenol A-epichlorohydrin condensate by Ciba having a melting point of130, an epoxide equivalent of 1,785, and a viscosity at 25 C.(Gardner-Holt) of Z.1.

The image obtained showed a maximum projection density of 3.00.

EXAMPLE VII Parts Formaldehyde polyvinyl acetal (82% acetal, 9.5-

13.0% acetate, ill-6.0% hydroxyl) 25 Uformite F-240 1 5 1,4-dioxanep-Diazo N,N-dimethyl aniline Zinc chloride salt 4 Acetonitrile 80 Aurea-formaldehyde resin available in clear, colorless form as 60- I-2%solids in xylol-butanol (1: 1 having an acid number solids basis 3-8,specific gravity 1.02, pounds per gallon 8.5, viscosity (Gardner-Holt at25 C.) L-Q, mineral thinner tolerance 50 min.

The image obtained had a maximum projection density of 2.75.

EXAMPLE VIII Parts Formaldehyde polyvinyl acetal (70% acetal, 22-30%acetate, 5.57.0% hydroxyl) 20 Cellulose acetate butyrate 6 1,4-dioxane200 p-Diazo N,N-dimethyl aniline zinc chloride salt 4 Acetonitrile 40The image obtained showed a maximum projection density of 2.34.

EXAMPLE 1X Parts Butyraldehyde polyvinyl acetal (80% acetal, 2.5%

acetate, 17.521.0% hydroxyl) 25 Nitrocellulose (RS) 3 1,4-dioxane 200Methyl ethyl ketone p-Diazo N,N-dimethyl aniline 4 Acetonitrile 40 Theimage obtained showed a maximum projection density of 2.74.

Ethyl cellulose can be used in place of nitrocellulose in the aboveformulation.

EXAMPLE X To illustrate the effect of varying amounts of resins A and B,three films were made accordding to the method of Examples VI-IX usingthe following:

Parts Polyvinyl formal 100 Dioxane 480 Dimethyl amino benzene diazoniumchloride, boron trifluoride stabilized 16 Acetonitrile 320 Polyvinylformal 100 Epon 1001 20 Dioxane 480 Dimethyl amino benzene diazoniumchloride, boron trifluoride stabilized 16 Acetonitrile 320 Polyvinylformal 100 Epon 1001 30 Dioxane 480 Dimethyl amino benzene diazoniumchloride, boron trifluoride stabilized 16 Acetonitrile 320 Epon 1001 isan epichlorohydrin bis phenol A type epoxy resin having a melting pointof 6476 C., an epoxide equivalent of 450-525, an average molecularWeight of 900-1000 and a viscosity of C. (Gardner-Holt) C-G.

Samples of the respective films were exposed on a sensitometer anddeveloped at 240 F. to make a copy of the step wedge of reversedphotographic sign. The following results were obtained.

(1) projection density (f/S aperture) of 2.0 l (2) projection density(f/S aperture) of 2.46 (3) projection density (f/5 aperture) of 2.7

The photographic contrast (gamma) decreased and the photographic speedincreased progressively from sample 1 through 3.

8 EXAMPLE XI The following formulation was used following the method ofExample I:

Parts Gelva (M-7, V100R) (polyvinyl acetate copolymer) Methyl ethylketone Distilled Water 5 General Electric Methylon 75108 4 p-DiazoN,N-dimethyl aniline zinc chloride salt 4 Acetonitrile 40 The followingthree formulations were used in making and using films, following themethod of Example I:

EXAMPLE XII Parts Gelva V-60 25 Epon 1001 5 Methyl ethyl ketone p-DiazoN,N-dimethyl aniline zinc chloride salt 4 Acetonitrile 40 Gelva V-60 isa homopolymer of vinyl acetate supplied in the form of granules whoseviscosity is 54-66 cps. in benzene solution containing 86 grams of resinper 1000 ml. of solution, determined at 20 C. with anOstwald-Cannon-Fenske viscometer, molecular weight (wt. av.) is 300,000,softening point is 385 F. (determined by a modified Kraemer and Sarnowmethod using 10 grams of mercury over a 6.35 mm. cylindrical plug ofGelva Resin in a 7 mm. diameter glass tube), heat seal temperature is-195 C. (the minimum temperature required for heat sealing of a 11.5 mil(dry) film cast from methanol solution on ditto paper dried at roomtemperature for 45 minutes, then force dried for one hour at 70 C.conditioned for 16 hours at 73 F., 50 percent R.H., using a PACK-RITE1.5 sec. dwell, 10 p.s.i. pressure, on 4" x A sample, face to face),maximum tensile strength is 6500 psi. (molded specimens2% gauge x A x0.07"conditioned 48 hours at 73 F., 50% RH. Instron Tester at 2 in./min.crosshead speed) percent elongation at yield is 4.8, abrasion resistanceis 59 mg. weight loss (Taber abrasion in mg. loss/1000 revs on cast filmconditioned 48 hours at 73 F., 50% RH, C-10 wheels-l000 gm. load), andsecond order transition temperature is 27 C.

EXAMPLE XIII Parts Gelva V-l00 25 General Electric Methylon 75108 5Methyl ethyl ketone 100 p-Diazo N,N-dimethyl aniline zinc chloride salt4 Acetonitrile 40 EXAMPLE XIV Parts Gelva V-800 25 Uformite F-240 5Methyl ethyl ketone 100 p-Diazo N,N-dimethyl aniline zinc chloride salt4 Acetonitrile 40 Gelva V-800 is a homopolymer of vinyl acetate suppliedin the form of granules whose properties, determined by the methodsstated in Example XII for Gelva V-60 are as follows: viscosity, 700-1000cps.; molecular weight, about 1.5 10 heat seal temperature, 205-215" F.;maximum tensile strength, 7300 p.s.i.; percent elongation at yield, 4.3;abrasion resistance, 59 mg. weight loss; second order transitiontemperature, 29 C.

As can be seen from the foregoing, the vesicular photographic filmsdescribed herein provide a useful means for controlling sensitivity andthe value of gamma. In addition, in the images obtained, the bubbles canbe made very small, thereby improving resolution and the bubbles haveunusually high stability. Thus it can be seen that these films have manyimportant advantages and achieve the objects of the invention.

The invention has now been described with respect to preferredembodiments, but it will be appreciated that various changes may be madein the materials used and the details of the processes, and that nolimitation thereto is intended, except as the invention is defined inthe appended claims. Thus, for example, while particular sensitizers aredescribed in the foregoing examples, any light decomposable solid agentof the type known in vesicular photography may be used, if it is of thetype which, upon exposure to light, decomposes into products which arevolatile upon warming to form the abovedescribed radiation-scatteringdiscontinuities. The preferred sensitizers are non-reactive to thevehicle and, upon exposure to light, decompose into products which arechemically non-reactive to said vehicle and which are volatile to formradiation-scattering discontinuities only in the light struck areas insaid vehicle to thereby furnish a record. Of the preferred sensitizers,those which are especially useful on exposure to light, particularly thediazonium salts. Full descriptions of these sensitizers may be found,for example, in US. Pat. 3,457,071, and the prior patents referred totherein, any of the sensitizers disclosed in said patent being usableherein.

Similarly other changes may be made in the process such as the kind oflight source used, the conditions of development, and the like, withinthe scope of the invention, since the examples herein are provided onlyfor the purpose of illustration.

What is claimed is:

1. A photographic material capable of furnishing a record solely in theform of a distribution pattern of radiation-scattering discontinuitiesformed within an otherwise substantially homogeneous vehicle, saidmaterial being in the form of a dry, water-resistant film, thecontinuous phase of said film being essentially a synthetic,water-insoluble, non-water swelling mixture of a resin A and a resin B,said mixture containing at least 50% by weight of resin A, said resin Abeing a polyvinyl alcohol in which at least 40% of the hydroxyl groupsare in the form of a member of the group consisting of acetals, withaldehydes containing up to about six carbon atoms and esters with anorganic carboxylic acid selected from the class consisting of aliphaticcarboxylic acids containing up to about six carbon atoms, mixturesthereof with higher aliphatic carboxylic acids, benzoic acid, naphthoicacid and phenyl acetic acid, and said resin B being an isocyanate resinwhich is an isocyanate-ended prepolymer derived by reaction of an excessof a polyisocyanate with a polyester, polyether or polyesteramide, and alight democposable solid agent substantially uniformly dispersed thereinas the sole essential decomposable agent, said decomposable agent itselfbeing non-reactive to said vehicle and upon exposure to lightdecomposing into products which are chemically non-reactive to saidvehicle and which are capable upon warming of forming saidrediation-scattering discontinuities only in the light struck areas insaid vehicle to thereby furnish said record.

2. A photographic material as set forth in claim 1 in which the amountof said resin A is less than 100% but at least 50% by weight of thetotal weight of resin A and resin B and the amount of said resin B is upto 50% by weight of said total weight.

3. A photographic material as set forth in claim 1 in which said resin Ais butyraldehyde polyvinyl acetal.

4. A photographic material as set forth in claim 1 in which said resin Ais formaldehyde polyvinyl acetal.

5. A photographic material as set forth in claim 1 in which said resin Ais a polyvinyl ester which is an ester of polyvinyl alcohol with anorganic carboxylic acid.

6. A method of producing a vesicular image which comprises,

exposing to image forming light a vesicular photographic materialcapable of furnishing a record solely in the form of a distributionpattern of radiation-scattering discontinuities formed within anotherwise substantially homogeneous vehicle, said material being in theform of a dry, water-resistant, non-Water swelling film, the continuousphase of said film being essentially a synthetic, water-insoluble,non-hygroscopic, non-water swelling mixture of a resin A and a resin B,said mixture containing at least 50% by weight of resin A, said resin Abeing a polyvinyl alcohol in which at least 40% of the hydroxyl groupsare in the form of a member of the group consisting of acetals withaldehydes containing up to about six carbon atoms and esters with anorganic carboxylic acid selected from the class consisting of alphaticcarboxylic acids containing up to about six carbon atoms, mixturesthereof with higher aliphatic carboxylic acids, benzoic acid, naphthoicacid and phenyl acetic acid and said resin B being an isocyanate resinwhich is an isocyanate-ended prepolymer derived by reaction of an excessof a polyisocyanate with a polyester, polyether or polyesteramide, and alight decomposable solid agent substantially uniformly dispersed thereinas the sole essential decomposable agent, said decomposable agent itselfbeing non-reactive to said vehicle and upon exposure to lightdecomposing into products which are chemically nonreactive to saidvehicle and which are capable upon warming of forming saidradiation-scattering discontinuities only in the light struck areas tothereby furnish said record, and

thereafter heating said photographic material to cause development.

7. A method as set forth in claim 6 in which the amount of said resin Ais less than but at least 50% by weight of the total weight of resin Aand resin B and the amount of said resin B is up to 50% by weight ofsaid total weight.

8. A method as set forth in claim 6 in which said resin A isformaldehyde polyvinyl acetal.

9. A method as set forth in claim 6 in which said resin A isbutyraldehyde polyvinyl acetal.

10. A method as set forth in claim 6 in which said resin A is apolyvinyl ester which is an ester of polyvinyl alcohol with an organiccarboxylic acid.

11. A method of producing a vesicular image which comprises,

exposing to image forming light a vesicular photographic materialcapable of furnishing a record solely in the form of a distributionpattern of radiation-scattering discontinuities formed within anotherwise substantially homogeneous vehicle, said material being in theform of a dry, water-resistant, non-water swelling film, the continuousphase of said film being essentially a synthetic, water-insoluble,non-hygroscopic, non-water swelling mixture of a resin A and a resin B,said mixture containing at least 50% by weight of resin A, said resin Abeing a polyvinyl alcohol in which at least 40% of the hydroxyl groupsare in the form of a member of the group consisting of acetals, withaldehydes containing up to about six carbon atoms and esters with anorganic carboxylic acid selected from the class consisting of aliphaticcarboxylic acids, containing up to about six carbon atoms, mixturesthereof with higher aliphatic carboxylic acids, benzoic acid, naphthoicacid and phen- 11 12 yl acetic acid and said resin B being an isocyanateheating said photographic material to cause developresin which is anisocyanate-ended prepolymer dement and the formation of a vesicularimage.

rived by reaction of an excess of a polyisocyanate with a polyester,polyether or polyesterarnide, and a References Cited light decomposablesolid agent substantially uniform- 5 UNITED STATES PATENTS ly dispersedtherein as the sole essential decomposable 3,032,414 5/1962 James et a196 49X agent, said decomposable agent itself being non-re- 3,081,1693/1963 Parker et aL 96 49X active to said vehicle and upon exposure tolight 3,143,418 ,8/1964 Priest et a1 decomposing into products which arechemically non- 3,190,844 6/1965 Milone et aL 260 2.5 reactive to saidvehicle and which are capable upon 10 3,208,350 9/1965 Daech Warming offorming said radiation-scattering disc0n- 3244523 4/1966 Growald et a1tinuities only in the light struck areas to thereby 3 2 0 599 7 9 5Lokker furnish said record, diffusing said volatile products from saidvehicle with NORMAN TORCHIN, Pnmary Exammer out forming an image i 15CHARLES L. BOWERS, 11s., Assistant Examiner subjecting said vehicle tosubstantially uniform irradiation to cause decomposition of anadditional quantity of said decomposable agent, and 96-49, 67, 88, 91,115

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Jan. 5, 1971Patent No. 3,55 Dated Imentofls) Norman '1. Notley, et al.

It is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

Delete from the heading in Column 1 the words:

"assignors to Kalvar Corporation, New Orleans,

La., a corporation of Louisiana" Signed and sealed this 20th day of June1972.

(SEAL) Attest R0 BERT GO TT SCHALK EDWARD M.FLETCHER, J'R. AttestingOfficer Commissioner of Patent

